Drive means for an endless rope, especially for ski lifts

ABSTRACT

A drive means for small portable ski lifts comprises a flanged motor-driven drive drum mounted at the upper station of the ski lift and frictionally driving an endless smooth rope adapted to be gripped by the skiers. The incoming reach of the rope passes around the drive drum in a first turn, then around an idle roller and finally in a second turn around the drive drum before leaving the drum. The drive drum is conical and the idle roller separated said turns is positioned radially outside the position on the circumference of the drum at which the incoming reach enters the drum and in approximately the same plane as the part of the conical drum having the smaller diameter.

United States Patent Luras 1 May 23, 1972 541 DRIVE MEANS FOR AN ENDLESS 2,646,005 7/1953 Swenson ..74/22s ROPE, ESPECIALLY FOR SKI LIFTS 682,395 9/1901 Wagner ..74/224 [72] Inventor: Arne Widar Luras, Sandsvaerveien 151, primary Examinelr Leonm-d Gerin 3600 Konssbers, Norway Attomey-l-lolman & Stem 22 F1 d: A 26 1970 l 1 l e 57 ABSTRACT 21 A LN 66,999 l 1 pp 0 A drive means for small portable ski lifts comprises a flanged motor-driven drive drum mounted at the upper station of the [30] Foreign Application Prio ity Dfllfl ski lift and frictionally driving an endless smooth rope adapted to be gripped by the skiers. The incoming reach of the rope Aug. 30, 1969 Norway ..3478/69 passes around the drive drum in a first then around an idle roller and finally in a second turn around the drive drum U.S.C1 before leaving the drum. The drive drum is conic a1 and the idle roller separated said turns is positioned radially outside [58] Field of Search ..74/224, 225, 228, 230.5 the position on the circumference of the drum at which the coming reach enters the drum and in approximately the same [56] References cued plane as the part of the conical drum having the smaller UNITED STATES PATENTS diameter- 660,7 83 10/1900 Wagner ..74/224 3 Claims, 2 Drawing Figures iATENTEUMAY 23 I912 3,664,205

SHEET 1 OF 2 INVENTOR BYM vA w/ ATTORNEYS DRIVE MEANS FOR AN ENDLESS ROPE, ESPECIALLY FOR SKI LIFIS BACKGROUND OF THE INVENTION.

driving the rope and an idle roller permitting the rope to be passed in two turns around the drum without interference between the two turns.

Small portable ski lifts require small drive drums for the endless rope. In order to achieve a sufficient frictional force it may therefore be desirable to increase the winding angle by passing the rope in two turns around the drum. However, this involves a risk of one turn crossing the other, whereby the rope will jam and break. The two turns must therefore be guided so as to be kept separate from each other. In this connection regard must be paid to the fact that when there is no load on the rope, the tension in the rope is small and the rope may therefore frequently swing from one side to the other.

For guiding the two turns it is known to use a drum having two separate grooves for keeping the two turns apart, vide: Norwegian Patent Specification No. 112.729. An idle roller positioned in approximately the same plane as the drum serves to guide the rope from one groove to the other. However, grooves in the drum result in a considerable wear on the rope, because of the flanges, beads or the like separating the grooves. Further, a guide means must be provided, guiding the incoming reach of the rope into the proper groove'even in the case of waves, swing or jerks in the rope.

BRIEF SUMMARY OF THE INVENTION.

The object of the present invention is to provide a drive means of the kind referred to, which in a simple way and with a minimum of wear separates the two turns so that the rope will not be jammed on the drum even if the rope swings.

According to the invention this is achieved by making the drive drum conical and by positioning the idle roller radially outside the position on the circumference of the drum at which the incoming reach enters the drum and in approximately the same plane as the part of the conical drum having the smaller diameter.

In order to ensure that the rope will pass properly over the drum and that the two turns will be kept apart even when the drive means is mounted in a slightly inclined position relatively to the direction of pull in the rope, the idle roller is preferably rotatably mounted in a bracket mounted so as to be pivotal and displaceable in relation to the drum, whereby the plane of the roller can be somewhat adjusted in relation thereto. Thereby the drive means may be adjusted so that irregularities in the positioning of the frame on which the drive means is mounted, are off-set.

The invention makes use of the fact that the rope will tend to climb onto the portion of the conical drum having the larger diameter. Thereby the first turn of the rope will stay at this end of the drum even if the drum has no grooves, but a smooth periphery. Since the idle roller is positioned radially outside the position at which the incoming reach of the rope enters the drum, there will not at this position exist two rope portions which could cross and jam as a result of swings or jerks in the incoming rope. This positioning of the idle roller also entails that the larger part of the winding angle of the rope around the drum is covered by the first turn, whereas the rope, when returning to the drum from the idle roller, will surround the drum with a winding angle of nearly 90 to 100. This fact, and also the fact that the tension in the rope within this turn and hence the force with which the rope is pressed against the drum are small, are responsible for the fact that within this second turn the rope does not have the same tendency to climb the portion having the larger diameter. If desired, the portion of the drum having the smaller diameter may be less conical and even cylindrical.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING.

FIG. 1 is a side view and FIG. 2 an end view of an embodiment of a drive means of the invention for a portable ski lift.

DETAILED DESCRIPTION.

The drawing illustrates a fragment of a frame 1 on which the drive means is mounted. The frame 1 carries a diagrammatically illustrated motor 2, which may, if desired, be provided with a gear. A drive drum 4 for an endless pulling rope 5 is attached to the shaft 3 of the motor 2. The frame 1 further carries a bracket 6 having two legs-7 in which an idle grooved roller 8 is rotatably mounted.

The frame 1 of course constitutes the upper station of the ski lift. The upward reach of the rope, which is identical to the reach entering the drive drum 4, enters the drum on the lower side thereof and follows the periphery of the drum for about 270 to 280. From this position the rope is passed to the roller 8, which has somewhat smaller diameter than the drive drum 4. The rope extends about 180 around the roller 8 in the same winding direction as around the drive drum 4 and then returns to the drum. After a turn of about on the periphery of the drive drum the rope finally leaves the drive drum and passes to an idle roller (not illustrated) in a lower station at the foot of the hill. From this station the rope again moves up the hill and back to the drive drum. When the ski lift is put under load by a skier gripping the upward reach of the rope, this reach will be tensioned whereas the reach leaving the drive drum and descending the hill will hang considerably looser and usually trail the ground.

As best illustrated in FIG. 2 the drum 4 is truncated. However, the best taper of the drum cannot be judged from the drawing, which is merely diagrammatical. The best value for the taper may be ascertained by experiments and may well be considerably less than illustrated in the drawing. The portion of the drum having the smaller diameter may also be approximately cylindrical or the taper may be smaller than for the remaining part of the drum.

As illustrated, the roller 8 is positioned in approximately the same plane as the part of the drum having the smaller diameter. The bracket 6 is secured to the frame 1 by a single bolt extending through an elongated aperture in the bracket 6, whereby the bracket may be displaced and pivoted in the interface between the bracket 6 and the frame 1.

The tension in the rope 5 will diminish from the position where the rope enters the drum 4, to the position where the rope leaves the drum. The rope being resilient, it will gradually contract, and the distance between two fixed points on the rope will be shorter during the second turn than during the first, which entails a slip between the rope and the drum if the speed of the drum is the same on the entire periphery. This induces wear and results in reduced efficiency. However, this tendency is counteracted by the fact that the second turn engages the drum on a portion of the periphery having smaller diameter.

What is claimed is:

1. A drive mechanism for an endless rope, especially for skilifts, comprising: a motor-driven flanged conical drive drum for frictionally driving said endless rope which is twice passed over the drum, said drum comprising a truncated conical profile; and an idle separating roller mounted with its axis substantially parallel to said of the drum, and disposed so that the roller is substantially coplanar with a lower diametered cross section of said conical drum towards its tapered end, so as to enable a portion of the rope to be passed around said separating idle roller to guide the rope, thereby preventing two turns of the rope passed around the conical drum from over-riding each other.

2. A drive mechanism according to claim I, wherein the roller is rotatably mounted in a bracket mounted so as to be pivotal and displaceable in relation to the drum, whereby the plane of the roller can be somewhat adjusted in relation to the drum.

3. A drive means as claimed in claim 1, wherein the conical drum includes a substantially cylindrical portion forming a 5 continuation of its smaller diameter. 

1. A drive mechanism for an endless rope, especially for skilifts, comprising: a motor-driven flanged conical drive drum for frictionally driving said endless rope which is twice passed over the drum, said drum comprising a truncated conical profile; and an idle separating roller mounted with its axis substantially parallel to said of the drum, and disposed so that the roller is substantially coplanar with a lower diametered cross section of said conical drum towards its tapered end, so as to enable a portion of the rope to be passed around said separating idle roller to guide the rope, thereby preventing two turns of the rope passed around the conical drum from over-riding each other.
 2. A drive mechanism according to claim 1, wherein the roller is rotatably mounted in a bracket mounted so as to be pivotal and displaceable in relation to the drum, whereby the plane of the roller can be somewhat adjusted in relation to the drum.
 3. A drive means as claimed in claim 1, wherein the conical drum includes a substantially cylindrical portion forming a continuation of its smaller diameter. 